Here’s how to repair a Denon S3000 CD player which gives “Disc read error”:

You don’t need to dissassemble the whole unit, only unmount the CD drive:

You’ll need to replace the laser pickup. According to the service manual, this player uses the Hitachi HOP-1200R (HOP-1200S and HOP-1200W are also compatible with this unit). I ordered the 1200R from eBay.

Remember to desolder the anti-static connections marked on the picture below:

Unscrew the metal top of the plastic rail holder and then you can pull out both rails and replace the pickup.